tomcat-nio

package com.zxz.pgdemo.controller;

import com.zxz.pgdemo.entity.User;
import com.zxz.pgdemo.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.List;

import static reactor.core.publisher.Signal.complete;

@Controller
@RequestMapping("/user")
public class UserController {
    @Autowired
    protected UserMapper userMapper;
    @RequestMapping(value = "/findByName", method = RequestMethod.POST)
    List<User> findByName(@RequestBody User user) {
        return userMapper.findByName(user.getUserName());
    }
    void export(HttpServletRequest request, HttpServletResponse response) throws IOException {
        ServletInputStream inputStream = request.getInputStream();
        ServletOutputStream outputStream = response.getOutputStream();
        AsyncContext asyncContext = request.startAsync();
        InputStream is = new FileInputStream("");
        outputStream.setWriteListener(new WriteListener() {
            @Override
            public void onWritePossible() throws IOException {
                byte[] buffer = new byte[4096];
                while(outputStream.isReady())
                {
                    int len=is.read(buffer);
                    if (len<0)
                    {
                        asyncContext.complete();
                        return;
                    }
                    outputStream.write(buffer,0,len);
                }
            }

            @Override
            public void onError(Throwable throwable) {
                asyncContext.complete();
                try {
                    is.close();
                    inputStream.close();
                    outputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
        });

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String info = request.getPathInfo();
        response.setContentType(request.getServletContext().getMimeType(info));
        File file = new File(request.getPathTranslated());
        response.setContentLengthLong(file.length());

        // Look for a file mapped buffer in the cache
        ByteBuffer mapped = cache.get(path);
        if (mapped == null) {
            try (RandomAccessFile raf = new RandomAccessFile(file, "r")) {
                ByteBuffer buf = raf.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, raf.length());
                mapped = cache.putIfAbsent(path, buf);
                if (mapped == null)
                    mapped = buf;
            }
        }

        // write the buffer asynchronously
        final ByteBuffer content = mapped.asReadOnlyBuffer();
        final ServletOutputStream out = response.getOutputStream();
        final AsyncContext async = request.startAsync();
        out.setWriteListener(new WriteListener() {
            public void onWritePossible() throws IOException {
                while (out.isReady()) {
                    if (!content.hasRemaining()) {
                        async.complete();
                        return;
                    }

                    out.write(content);
                }
            }

            @Override
            public void onError(Throwable t) {
                request.getServletContext().log("Async Error", t);
                async.complete();
            }
        });
    }
}